More R12 AC help needed

[Diabolic]

93 F150 with Mark VIII fan on high.
Static pressure low side 110
Idle low side 55psi, high side 190
Ambient temp 96
Vent temp 84

Is this a sign of a weak compressor? It has made a tapping sound for the past 4 years but cooled just fine. It still cools fine 2000 rpm and up, but below that it's lousy.

[Diabolic]

Fug it I'm switching to 134. Where can I get a compressor at a good price? I'm going to get the main hose made at Wayne's in Keller since it's long discontinued for the Lightning. New condenser, drier, and oriface tube. Make it easier in the future. The entire system is original 1993.

[Chili]

I just got the R12 - R134a conversion fittings from AZ yesterday, and topped it off with 134 and it is cooling nicely (90 Mustang). Low side was in the 40's high side was below 300 with ambient temps at 95 or so. I understand that it may not be a long term solution but I figure the same parts will need to be replaced if it mucks it up anyways (to truly convert), so even if it only buys a little time, so be it.

Fittings were like $12, can of 134 the same.

I already had 134 gauges, fwiw.

[Chili]

BTW.. You should be testing pressures at 1500 RPMs, shouldn't you? If testing with the engine off, low and high side pressures should be roughly the same? Not that I really know wtf I'm talking about.